The present invention relates to an optical system, and particularly to an optical system for use in an electrostatic copier of the type in which a document is scanned as it moves through an object plane, and an image transmitted to a photosensitive element which is moving through an image plane.
There is an existing need in the photocopying arts for image transmitting systems which clearly and accurately transmit an image, while minimizing the housing necessary for packaging the photocopying apparatus.
Optical systems which are typical of the prior art may be found in U.S. Pat. Nos. 3,605,593 (Anderson), 3,113,484 (Baker), 2,953,980 (Montebello), 2,736,235 (Toulon), 3,221,591 (Schepler), 3,447,438 (Kaufer et al) 2,573,242 (Bonnet), and British patents 1,200,383 and 26,820.
Optical systems in current use in connection with customary sheet sizes usually employ lenses whose focal lengths are five inches or more, and a focal length of this order represents a light path of about 20 inches or more.
Materially shortening this light path by means of a shorter focal length lens is not possible within the bounds of current technology, because the widest angle lenses which can be constructed in the shorter focal length range are not capable of spanning an ordinary sheet width such as 81/2 inches.